Galba (Sibirigalba) sibirica ( Westerlund, 1885 )

Marinskiy, Vadim V., 2017, Checklist of the freshwater snails (Mollusca: Gastropoda) of Mongolia, Zootaxa 4317 (1), pp. 45-78 : 54-56

Galba (Sibirigalba) sibirica ( Westerlund, 1885)

( fig. 4 D, E)

Regional distribution. Two localitieS of Galba sibirica in Mongolia haVe been reVealed during our Study. 1. WeStern Mongolia, Teellin gol RiVer (19.07.2012, leg. M. VinarSki), and 2 . ÖVörkhangai aimag, a brook Situated 30 kilometerS SW from ArVayheer Settlement (05.06.2010, leg. D.M. PalatoV). PopoVa (1981) found G. sibirica in the PleiStocene depoSitS of Mongolia .

Extra-limital distribution. ThiS SpecieS iS widely diStributed in WeStern and EaStern Siberia aS well aS in the RuSSian Far EaSt and northeaStern China ( KrugloV & StarobogatoV 1985b; BogatoV & ZatraVkin 1990; AndreyeVa et al. 2010). It iS Still known from a limited number of localitieS. PoSSibly, howeVer, that preceding authorS, working with empty ShellS only, confuSed it with G. truncatula .

Remarks. ThiS poorly known SpecieS waS deScribed by WeSterlund (1885) from the extreme North of Siberia, and itS type SerieS repreSentS a mixture of juVenile ShellS of Galba and Lymnaea (VinarSki et al. 2013) . KrugloV & StarobogatoV (1985b) re-deScribed thiS Snail and reported clear anatomical differenceS between it and conchologically Similar G. truncatula (O.F. Müller, 1774) . VinarSki et al. (2013) examined the type SerieS of Limnaea truncatula Var. sibirica and deSignated the lectotype.

Since G. sibirica iS not well-Studied, below we giVe Some remarkS concerning itS differential featureS and taxonomic identity.

Galba sibirica reSembleS G. truncatula but differS from the latter by conVex but not Stepped whorlS and relatiVely lower Spire ( KrugloV & StarobogatoV 1985b; Khokhutkin et al. 2009; AndreyeVa et al. 2010). BeSideS, G. sibirica iS of Significantly leSS Size. ItS Shell height typically doeS not exceed 7.5 mm ( Table 4), whereaS in G. truncatula thiS parameter may reach 10–12 mm. The lectotype Shell (juVenile) iS of 3.6 mm height only (VinarSki et al. 2013).

Anatomically, G. sibirica iS characterized by a narrow and relatiVely long peniS Sheath, while G. truncatula haS the copulatory apparatuS with a Short and more or leSS thick peniS Sheath (compare figS. 4 E and F).

SpecimenS of G. sibirica from Mongolia Studied by uS (Teellin gol RiVer) Showed Some Variability in their Shell proportionS. On the baSiS of their meaSurementS, Some of theSe ShellS may be identified aS belonging to G. (S.) potanini (KrugloV et StarobogatoV, 1985) deScribed from Northern China (OrdoS Plateau). The latter SpecieS iS Still known after the original deScription only and itS intraSpecific Variation in both conchological and anatomical traitS haS not been Studied. It iS not impoSSible that G. potanini iS a junior Synonym of G. sibirica though we do not poSSeSS enough material to maintain it definitely.

Figures

FIGURE 4. Shells and genitalia of the lymnaeid snails discUssed in the paper. A— Lymnaea stagnalis (31.07.1982, floodplain of the Orkhon River, leg. Mikhailov). B— L. stagnalis (15.07.2012, Chono-Khoraikhgol River, leg. Vinarski). C— Ladislavella terebra (31.07.1982, floodplain of the Orkhon River, leg. Mikhailov). D, E— Galba sibirica (19.07.2012, Teellin-gol River, leg. Vinarski). F— G. truncatula, the copUlatory apparatUs (25.02.2010, Abkhazia, Gagra District, Wet shore of Inkit Lake, leg. Palatov). G – Radix auricularia (19.07.2012, Teellin-gol River, leg. Vinarski). H— Radix bactriana (13.07.2012, Khar Us NUUr Lake, leg. Vinarski). I— R. parapsilia (09.06.2009, Khovd River, leg. Maryinskiy). J— R. mongolica (13.07.2012, Khar Us NUUr Lake, leg. Vinarski). K— R. mongolica, a scalarid specimen (Hövsgöl Lake, leg. et det. Sitnikova, LIN). L— R. balthica (20.07.1967, Khar Dorgon NUUr Lake, leg. Zhaltsanova). M— R. intermedia, a paralectotype of Limnaea eversa (1877, Eter River near Dja-Dzassyk Monastery, leg. Potanin, ZIN). Scale bars 1 mm (E, F), 2 mm (C, I, J, K), 5 mm (A, B, G, H, L, M).